共に強く： 励起子とポラリトンの結合でより優れた太陽電池と高輝度LEDを実現(Stronger Together: Coupling Excitons to Polaritons for Better Solar Cells and Higher Intensity LEDs)

2024-08-06 米国国立再生可能エネルギー研究所(NREL)

＜関連情報＞

• https://www.nrel.gov/news/program/2024/stronger-together-coupling-excitons-to-polaritons-for-better-solar-cells-and-higher-intensity-leds.html
• https://pubs.acs.org/doi/10.1021/acs.jpclett.3c03452

励起子-ポラリトン結合を利用した2次元ペロブスカイトにおける励起子/励起子再結合の制御 Controlling Exciton/Exciton Recombination in 2-D Perovskite Using Exciton–Polariton Coupling

Rao Fei,Matthew P. Hautzinger,Aaron H. Rose,Yifan Dong,Ivan I. Smalyukh,Matthew C. Beard,and Jao van de Lagemaat
The Journal of Physical Chemistry Letters  Published:February 7, 2024
DOI:https://doi.org/10.1021/acs.jpclett.3c03452

Abstract

In this paper, we demonstrate that exciton/exciton annihilation in the 2D perovskite (PEA)₂PbI₄ (PEPI)─a major loss mechanism in solar cells and light-emitting diodes, can be controlled through coupling of excitons with cavity polaritons. We study the excited state dynamics using time-resolved transient absorption spectroscopy and show that the system can be tuned through a strong coupling regime by varying the cavity width through the PEPI layer thickness. Remarkably, strong coupling occurs even when the cavity quality factor remains poor, providing easy optical access. We demonstrate that the observed derivative-like transient absorption spectra can be modeled using a time-dependent Rabi splitting that occurs because of transient bleaching of the excitonic states. When PEPI is strongly coupled to the cavity, the exciton/exciton annihilation rate is suppressed by 1 order of magnitude. A model that relies on the partly photonic character of polaritons explains the results as a function of detuning.